NORTH-SOUTH CENTRE - ETH - North-South Centre North-South ...

Analysis and initial exploitation of
resistance to wheat stem rust race Ug99
This project aims at (i) identifying improved wheat germplasm
resistant to Ug99 race of stem rust, and (ii) characterising
“Avocet/Pavon 76” mapping population for stem rust.
Seven of the good lines selected from the Advanced Yield
Trials (AYT) were forwarded to the National Performance Trial
Committee (NPTC) for final testing before release as varieties
in Kenya. These seven lines were planted in ten sites
across the wheat growing areas in Kenya. We obtained data
on yield, test weight and quality aspects. In terms of yield,
lines KSRR6 and KSRR7 were the best at 1.7 tons/ha and 1.6
tons/ha respectively. They did better than the best check by
over 50% and will likely be released after another season of
testing. Line KSRR2 was evaluated for the second season. It
performed better than the best check by 19% and was released
as a variety (Kenya Robin). We are now multiplying
the seeds for this variety so that they will be available to
farmers by October 2010. Two more lines will be released
early this year. In terms of quality, all the seven lines have
flour extraction of above 70%, loaf volume of above 500cc,
protein content of above 10%. This is very acceptable for
bread-making.
180 recombinant inbred lines (RILs) of the original
Avocet/Pavon 76 mapping population were planted in the
main season of 2008, off-season of 2008–2009 and main
season of 2009. During these three seasons, the disease
severity has been too low to obtain good phenotypic data.
In 2008 main season, the problem occurred due to an accidental
application of fungicide. The 2008–2009 off-season
and 2009 main-season were marked by extreme drought
in Kenya. This caused poor plant and rust development.
The experiment was replanted again in 2009–2010 offseason
in order to obtain a second year of reliable data.
Of the 180 RILS, 92 were sent for diversity array technology
(DArT) analysis with 458 markers distributed across all
the chromosomes. A tentative map for the population has
been developed using mapmaker. The process of identifying
quantitative trait locus (QTL) for stem rust resistance
is in progress. However, we still need more phenotypic and
simple sequence repeats (SSR) marker data. In the case
of microsatellite markers, 96 SSR were used to screen the
parental lines using LI-COR 4200 DNA analyser. Five SSRs
were found to be polymorphic for both parents. These were
ran on the 180 lines and used for mapping together with
the DArT markers.
Research fellow
Peter Njoroge Njau,
University of Zurich, Switzerland
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Supervisors
Beat Keller, University of Zurich, Switzerland;
Ravi P. Singh, CIMMYT, Mexico
Collaborator
Macharia Gethi, KARI, Kenya
Duration
January 2007 – March 2010
Capacity development
Research fellowships
Blocks of the new wheat lines at a trial site in Timau, Kenya